What does the filiform apparatus do at the entrance into ovule?

Options

A. It helps in the entry of pollen tube into a synergid
B. It prevents entry of more than one pollen tube into the embryo sac
C. It brings about opening of the pollen tube
D. It guides pollen tube from a synergid to egg

Explanation

### Step-by-Step Solution:

1. **Understanding the Filiform Apparatus**: The filiform apparatus is a structure found in the ovule of flowering plants. It is an extension of the synergids, which are specialized cells located at the micropylar end of the embryo sac.

2. **Role in Pollen Tube Guidance**: The primary function of the filiform apparatus is to guide the pollen tube towards the synergids. When a pollen grain lands on the stigma, it germinates and forms a pollen tube that grows down through the style towards the ovule.

3. **Facilitating Entry into Synergids**: As the pollen tube approaches the ovule, the filiform apparatus helps in the entry of the pollen tube into one of the synergids. This is crucial for the fertilization process, as the pollen tube carries the male gametes.

4. **Preventing Multiple Pollen Tubes**: While the filiform apparatus does not directly prevent multiple pollen tubes from entering the embryo sac, it plays a role in ensuring that only one pollen tube successfully enters a synergid. This is important for successful fertilization.

5. **Not Responsible for Pollen Tube Opening**: The filiform apparatus does not bring about the opening of the pollen tube; this occurs at the tip of the pollen tube itself as it enters the synergid.

6. **Guidance to the Egg Cell**: The filiform apparatus does not guide the pollen tube from the synergid to the egg cell. The pollen tube delivers the male gametes to the egg cell directly after entering the synergid.

### Conclusion:
The primary function of the filiform apparatus is to help in the entry of the pollen tube into a synergid, facilitating the fertilization process.